Candida albicans is an opportunistic fungal pathogen that causes a variety of serious infections in humans, especially in immunocompromised hosts. These infections have increased in the past few decades primarily due to improved immunosuppressive therapies, high-intensity chemotherapy strategies in cancer patients and aggressive medical treatments in intensive care units. Currently available treatment strategies for these infections have several limitations including antifungal resistance, toxicity, drug interactions, high-cost, and severe side effects. New antifungal drugs with new molecular targets are greatly needed. At the National Center for Natural Products Research, we have identified several novel compounds from natural sources that have potent activity against C. albicans. The overall goal of this project is to elucidate the molecular effects exerted by these novel compounds as a starting point towards the development of novel antifungal therapies. The specific aims of this proposal are: (1) Identify molecular pathways affected by novel antifungal compounds with activity against Candida albicans using genomic profiling approaches. We will analyze 4 novel natural products using two parallel genomic profiling approaches - transcript profiling and fitness profiling. Results from the two combined approaches will be utilized to implicate pathways that play an important role in mediating drug effects, (2) Evaluate molecular pathways identified in aim #1 for their potential as targets of the antifungal compounds tested. The molecular pathways identified will be evaluated by analyzing mutants in which individual target genes are deleted or overexpressed. Altered susceptibility to the test compound will give an indication that the target gene is critical for drug activity. The proposed work will suggest new pathways for utilization in the discovery and development of new classes of antifungal agents for C. albicans infections. This will also broaden the understanding of the basic biology of this pathogen, including potential information on cell survival pathways, pathogenesis, virulence, and resistance mechanisms. This exploratory work will provide information for future research including (a) structural modification of tested compounds to improve activity or selectivity, (b) further genetic and biochemical work to identify specific drug targets, (c) analysis of additional antifungal compounds present in our repository, and (d) expansion into additional fungal pathogens such as non-albicans Candida species, Cryptococcus neoformans and Aspergillus fumigatus. Novel antifungal drugs are urgently needed for clinical use because of the following reasons: (i) current drugs are suboptimal due to toxicity and resistance problems, (ii) fungal infections pose a serious public health problem, and are on the rise in immunocompromised patients (e.g., organ transplant recipients and patients infected with human immunodeficiency virus), (iii) drug-resistant fungal strains are increasing, and (iv) new fungal pathogens are continuing to emerge. The overall goal of this project is to elucidate the molecular effects exerted by four novel antifungal compounds that have strong activity against the yeast Candida albicans that causes serious infections in humans. This work will provide a starting point in the development of new antifungal therapies. [unreadable] [unreadable] [unreadable]